Reactive flame retardant blends for flexible polyurethane foam

ABSTRACT

The present invention provides dialkyl phosphorus-containing compounds, namely reactive mono-hydroxyl-functional dialkyl phosphinates in a blend with a phosphate compound, said blend serving as highly efficient reactive flame retardant blend in flexible polyurethane foam. The invention further provides fire-retarded polyurethane compositions comprising said the reaction product of the flame retardant blend with polyol and isocyanate foam forming components.

This application is a divisional of U.S. patent application Ser. No.16/041,982, filed Jul. 23, 2018; which claims the benefit of U.S.provisional patent application Ser. No. 62/561,365, filed Sep. 21, 2017,the entire contents of which are incorporated by reference herein.

FIELD OF THE INVENTION

The disclosure herein provides for the use of reactive dialkylphosphorus-containing compounds, namely hydroxyl-functional esters ofdialkyl phosphinic acids, which when reacted with polyol and isocyanate,serve as highly efficient reactive flame retardants in flexiblepolyurethane foams. The invention further provides fire-retardedflexible polyurethane foam with said hydroxyl-functional dialkylphosphinates reacted and incorporated into the polymer matrix of aflexible polyurethane foam. The expressions “fire retardants” and “flameretardants” are used herein interchangeably.

BACKGROUND OF THE INVENTION

Brominated or phosphorus-based flame retardants are known to be highlyeffective and, in many cases, are the only options for reducing the firerisk of synthetic materials such as flexible polyurethane foams.However, the growing public and governmental scrutiny of chemicals, andin particular flame retardants, has increased over the years. The goalis towards more sustainable, reactive, polymeric and/or halogen-free newproducts. Scrutiny greatly diminishes if a flame retardant is reactedinto the polymer matrix and cannot be leached-out.

Thus, there is a demand for reactive phosphorus-containing fireretardants for flexible polyurethane possessing such features as highphosphorus content, clear light color and good compatibility withpolyether polyols and polyester polyols employed in the polyurethaneindustry.

SUMMARY OF THE INVENTION

The present invention provides a flame retardant blend comprising (1)reactive dialkyl phosphorus-containing mono-hydroxyl-functional compoundand (2) a phosphate compound, said flame-retardant blend possessinghighly satisfactory flame-retarding characteristics and having goodcompatibility with the polyol components of a flexible polyurethanefoam-forming system. The expression “a flexible polyurethanefoam-forming system” as used herein shall be understood to comprise apolyol, an isocyanate and the flame retardant blend(s) as describedherein. The mono-hydroxyl-functional dialkyl phosphinate compounds arefully reactive through their single hydroxyl-functional group, and canbe more easily formulated than di- or tri-hydroxyl-functional dialkylphosphinate compounds. It has been surprisingly found that despite itslower content of hydroxyl-functionality, the reactive mono-hydroxylfunctional dialkyl phosphinate compounds herein can be reacted andincorporated into the polymer structure of a flexible polyurethane foam,e.g., by reaction with the isocyanate component of the flexiblepolyurethane foam-forming system, without disrupting the elasticproperties of the flexible polyurethane foam. This means that the flameretardants of the invention become integrated into the flexible foamsubstrate, such that they are not released into the environment and arenot likely to penetrate through cell membranes of living tissue, andtherefore do not pose a health hazard. The invention further providesthe flexible polyurethane foam-forming system described above, includingbut not limited to the reactive dialkyl phosphorus-containingmono-hydroxyl-functional compounds described herein.

The applicants herein have discovered an unexpected synergisticrelationship between the mono-hydroxyl-functional dialkyl phosphinatecompounds described herein and phosphate compounds, such as phosphateesters. These phosphinate/phosphate ester blends contain less phosphorusthan just a mono-hydroxyl-functional dialkyl phosphinate compound alonebut still retain the same flame retardant efficiency. Further applicantshave discovered that this synergistic property extends to a variety ofphosphate ester products which can be combined withmono-hydroxyl-functional dialkyl phosphinate.

In addition to holding the flammability performance at a high level withthese synergistic flame retardant blends, applicants have alsodiscovered the unexpected improvement in physical properties of theresulting foams (e.g., compression set) which are greatly improved overwhat is observed using the mono-hydroxyl-functional dialkyl phosphinatecompounds alone. Reactive flame retardant products are known in the artto disrupt the normal foam-forming process, resulting in poor foamphysical properties. In most cases this is observed by a loss of thefoam's ability to recover after compression at an elevated temperature.Compression set testing according to ASTM D3574 is a common foamrequirement, and ensures compressed foam will indeed rebound. By using asmall amount of the mono-hydroxyl-functional dialkyl phosphinatecompounds in the phosphinate/phosphate ester flame retardant blends, thenegative effects of using a reactive flame retardant product can beavoided while at the same time still retaining the high flame retardantefficiency required in the end use application. The flame retardantblends surprisingly retain both excellent FR performance and also goodphysical properties.

The term “foam” as used herein refers to flexible polyurethane foams.The flexible polyurethane foam described herein, or claimed herein, ascomprising, consisting essentially of, or consisting of the reactedmono-hydroxyl-functional dialkyl phosphinate compounds of the generalformula (I-A) and/or (I-B), the phosphate compound, and a group ofphosphorus-containing diol and/or polyol reaction products of thepartial phosphorylation of polyalcohols, which contains at least onephosphorus-containing group of the general formula (I-B) are allunderstood herein to contain the aforementioned formula(e) as reactivematerials, i.e., the aforementioned formula(e) are reacted into theflexible polyurethane material's structure, in which case theaforementioned formula(e) may not be present, or would not be present inthe same structural formula(e) as described herein, but would be presentin the flexible polyurethane material as a reaction product of a dioland/or polyol, an isocyanate and the structural formula(e) describedherein.

The term “polyol” as used herein will be understood as also possiblybeing defined as a diol and/or a polyol.

The flame retardant blend of the present invention provides aflame-retardant effective amount of (A) mono-hydroxyl-functional dialkylphosphinate compounds of the general formula (I-A) and (I-B), and agroup of phosphorus-containing diol and/or polyol reaction products ofthe partial phosphorylation of polyalcohols, which contains at least onephosphorus-containing group of the general formula (I-B), and (B)phosphate compound, wherein formula (I-A) is:

wherein:

R¹ and R², are selected from a linear or branched alkyl group containingfrom 1 to 4 carbon atoms, such as methyl, ethyl, propyl, isopropyl,butyl, and isobutyl, preferably methyl or ethyl, more preferably both R¹and R² being ethyl; and,

X is either

and when X is —(Z)_(k)—R³, Z is —(Y—O)_(n)—, wherein Y is a linear orbranched alkylene group containing from 2 to 8 carbon atoms, preferablyfrom 2 to 4 carbon atoms, more preferably ethylene, propylene, orisopropylene, and n represents an integer from 1 to 20, preferably from1 to 5, and even more preferably from 1 to 2.

k may be 0 or 1;

R³ is selected from hydrogen, a mono-hydroxy-terminated linear orbranched alkylene group containing from 2 to about 8 carbon atoms,preferably from 2 to 4 carbon atoms; and,

provided that when k is zero, R³ is the mono-hydroxy-terminated linearor branched alkylene group and when k is 1, R³ is hydrogen, and

when X is

R⁴ and R⁵ are each independently selected from H, a linear or branchedalkyl group containing from 1 to 8 carbon atoms, preferably from 1 toabout 4 carbon atoms, and most preferably any one of methyl, ethyl orpropyl, a linear or branched alkenyl group containing from 2 to 8 carbonatoms, preferably from 2 to about 4 carbon atoms, a halo-substitutedalkyl group containing from 1 to 8 carbon atoms, an alkoxy groupcontaining from 1 to 8 carbon atoms, preferably from 1 to about 4 carbonatoms, an aryl group containing from 6 to 12 carbon atoms, preferablyfrom 6 to about 8 carbon atoms, and an alkylaryl group containing from 7to 16 carbon atoms, preferably from 7 to about 12 carbon atoms, or R⁴and R⁵ are bonded to each other to form a cycloalkyl group containingfrom 4 to about 8 carbon atoms, preferably 6 carbon atoms; and whereinformula (I-B) is:

wherein:

R¹ and R², are independently selected from a linear or branched alkylgroup containing from 1 to 4 carbon atoms, such as from methyl, ethyl,propyl, isopropyl, butyl, and isobutyl, preferably methyl or ethyl, morepreferably both R¹ and R² both being ethyl; and,

n¹ is an integer equal to or greater than 1, and n² is one, preferablyn¹ is from about 1 to about 5 and

Z² is a moiety derived from a diol or polyol which has a valence ofn¹+n², and is of the general formula:

wherein R is selected from the group consisting of:

and where each R⁶ independently is H or is an alkyl of from 1 to 4carbon atoms, x is 0 or ≥1, preferably 1 to 4, more preferably x=1, y is2 or 3; z is an integer of from 2 to 5; and, m≥1, preferably m=1.

There is also provided herein a process for the preparation of thesecompounds.

The compounds of formula (I-A) can be prepared by the reaction ofmono-hydroxyl-functional-dialkyl phosphinic acids of formula (II) withcompounds having an oxirane group, wherein formula (II) is:

wherein R¹ and R² are as defined.

The compounds of formula (I-A) can also be prepared by the reaction ofdialkyl phosphinic halides of formula (III) with aliphatic diols,wherein formula (III) is:

and wherein R¹ and R², are as defined, and A is chlorine or bromine.

The phosphorus-containing diols and/or polyols of the invention, forexample those of formula I-B, can be prepared by the reaction of dialkylphosphinic halides of formula (III) with aliphatic diols and/or polyols.

The reactive mono-hydroxyl-functional dialkyl phosphinates of thisinvention possess high phosphorus content, have good hydrolytic andthermal stability, exhibit good compatibility with the diol and/orpolyol components of the flexible polyurethane foam-forming system, andare useful as highly efficient reactive flame retardants in flexiblepolyurethane foams.

The present invention further provides fire-retarded flexiblepolyurethane comprising the reactive residue of saidphosphorus-containing mono-hydroxyl-functional compounds and phosphatecompound after being reacted in the flexible polyurethane foam-formingsystem to form the flexible polyurethane foam. The phosphorus-containingmono-hydroxyl-functional compounds herein can be used in the flexiblepolyurethane foam-forming system either individually or in an admixturewith one another, and/or with other flame retardants, includinghalogen-containing flame retardants and phosphorus-containing flameretardants.

All the above and other characteristics and advantages of the inventionwill be better understood through the following illustrative andnon-limitative detailed description of the preferred embodimentsthereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graphical depiction of the first set of data in ApplicationExample 4, i.e., RPE/BPPE blends.

FIG. 2 is a graphical depiction of the second set of data in ApplicationExample 4, i.e., RPE/BDP blends.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In one embodiment the mono-hydroxyl-functional dialkyl phosphinates offormula (I-A) can be those of the more specific formulae (I-A-1) or(I-A-2), wherein formula (I-A-1) is:

wherein R¹ and R², Z, k, and R³ are as defined above; and,

wherein formula (I-A-2) is:

and wherein R¹, R², R⁴ and R⁵ are as defined above.

In one embodiment herein, the mono-hydroxyl-functional dialkylphosphinates of formula (I-A) of the present invention are prepared bythe reaction of dialkyl phosphinic acids of formula (II) with compoundsof formula (IV), having oxirane groups, which formula (IV) is

wherein:R⁴ and R⁵ are as defined above.

In one other embodiment herein, the mono-hydroxyl-functional dialkylphosphinates of formula (I-A) of the present invention are prepared bythe reaction of dialkyl phosphinic halides of formula (III) withaliphatic diols of formula (V):

HO—(Z)_(K)—R³  (V)

wherein Z, R³ and the subscript k are as defined above.

The phosphorus-containing diols and/or polyols of the present invention,for example those of formula (I-B), are prepared by the reaction ofdialkyl phosphinic halides of formula (III) with aliphatic diols orpolyols.

The dialkyl phosphinic acids (II) and dialkyl phosphinic halides (III)employed as starting materials in the process of the present inventionare for the most part well known in the art. The compounds of formula(II) can be obtained for example by hydrolysis of the correspondingdialkyl phosphinic halides (III). The latter can be prepared for exampleby the method described in U.S. Pat. No. 3,104,259, the entire contentsof which are incorporated by reference herein.

Specific oxirane compounds used in the process for preparing thecompounds of formula (I-A) or more specifically (I-A-1) or (I-A-2) ofthe present invention are selected from the group consisting of, but notlimited to, for example, ethylene oxide, propylene oxide,1,2-epoxybutane, 1,2-epoxypentane, 1,2-epoxyhexane, 1,2-epoxy-5-hexene,1,2-epoxy-2-methylpropane, 1,2-epoxyoctane, glycidyl methyl ether,glycidyl isopropyl ether, glycidyl isobutyl ether, glycidyl heptylether, glycidyl 2-ethylhexyl ether, glycidyl allyl ether,trimethylolpropane triglycidyl ether, styrene oxide, cyclohexene oxide,epichlorohydrin and combinations thereof. More preferably, ethyleneoxide, propylene oxide and 1,2-epoxybutane are used as the oxiranecompound.

Specific aliphatic diols used in the process for preparing the compoundsof formula (I-A) or more specifically (I-A-1) or (I-A-2) of the presentinvention are selected from the group consisting of, but not limited to,for example, ethylene glycol, diethylene glycol, triethylene glycol,propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-propanediol, 1,4-butane diol, 2-butene-1,4-diol, 1,5-pentane diol, 1,6-hexanediol, 1,8-octane diol, and other diols having molecular weights up to700.

The aliphatic diols and/or polyols used in the process for preparing thephosphorus-containing polyols of the invention can generally be anysuitable diols and/or polyols having at least two or at least threereactive hydrogen atoms, respectively, examples being those havingfunctionality of from 2 or 3 to 6, preferably, 2, 3 and 4, andpreferably a molecular weight of from about 100 to about 700. Specificaliphatic diols and/or polyols can be selected from the group ofnon-polymeric polyalcohols, for example, trimethylol propane,trimethylol ethane or glycerol.

Preferably, the diols and/or polyols to be used according to the presentinvention are polyether diols and/or polyols. This class of diols and/orpolyols is obtained by the ring-opening addition reaction of one or morealkylene oxides (e.g., ethylene oxide and propylene oxide) with asuitable reactant containing one or more active hydrogen atoms, such asalcohols, amine and acids; more specifically, said reactant may beselected from a group consisting of diols, triols, novolac resins,pentaerythritol, sorbitol, sucrose, diethylenetriamine and the like.Polyester-polyols may also be used according to the present invention;this class of polyols is obtained by the condensation reaction ofcarboxylic, dicarboxylic (or polycarboxylic) acid, such as adipic acid,phthalic acid or the like, with diols or triols. The aliphatic diolsand/or polyols used in the process for preparing thephosphorus-containing mono-ols, diols or polyols of the presentinvention are selected from polymeric diols and/or polyols such aspolyether polyols, polyester polyols, and mixtures thereof.

In a preferred embodiment of the present invention, the reaction ofdialkyl phosphinic acids (II) with an oxirane compound is carried out ina medium of excess oxirane, with or without an organic solvent such astetrahydrofuran, 1,4-dioxane, or toluene.

The amount of oxirane compound used in the reaction with mono-hydroxydialkyl phosphinic acids (II) is a 5-300% molar excess relative to themono-hydroxy dialkyl phosphinic acid, and preferably a 50-100% molarexcess. Using a molar excess of the oxirane compound greater than 100%relative to the mono-hydroxy dialkyl phosphinic acid is inexpedient dueto the need to recycle a large quantity of oxirane.

The mono-hydroxyl-functional dialkyl phosphinates of formula (I-A) ormore specifically (I-A-1) or (I-A-2) of the present invention have aphosphorus content of about 8-18% by weight and a hydroxyl number ofabout 150-315 mg KOH/g, depending on the dialkyl phosphinic acid and theoxirane taken for the reaction.

It is preferred, for the preparation of the targetmono-hydroxyl-functional dialkyl phosphinates (I-A) or more specifically(I-A-1) or (I-A-2) with the highest possible phosphorus content, toreact mono-hydroxy-dialkyl phosphinic acids having the highestphosphorus content amongst the mono-hydroxy dialkyl phosphinic acids(II), with ethylene oxide and propylene oxide.

Thus, the compounds of formula (I-A) or more specifically (I-A-1) or(I-A-2), having particularly valuable properties are those wherein R′,and R² are each ethyl.

Said reactions are carried out at a temperature of between 40° C. and120° C., and preferably between 70° C. and 90° C. At a temperature lowerthan 40° C. the reaction becomes unacceptably slow. On the other hand,applying a temperature higher than 120° C. is not advisable since atsuch temperatures undesirable decomposition products may be formed.

In a preferred embodiment, the reaction of dialkyl phosphinic halides(III) with an aliphatic diol is carried out in a medium of excess diol.

The amount of diol compound used in the reaction with dialkyl phosphinichalides (III) is generally 2 to 10 moles per 1 mole dialkyl phosphinichalide, and preferably a 4 to 8 moles molar excess. The relatively largeexcessive amounts of these diols are required for minimizing theformation of undesirable bis(dialkyl phosphinate) esters of glycols anddiols having no hydroxyl groups. Using a molar excess of the diolcompound greater than 10 moles per 1 mole dialkyl phosphinic halide isinexpedient due to the need to recycle a large quantity of diol.

The mono-hydroxyl-functional dialkyl phosphinates of formula (I-A) ormore specifically (I-A-1) or (I-A-2) of the present invention have aphosphorus content of about 2-18% by weight and a hydroxyl number ofabout 150-450 mg KOH/g, depending on the dialkyl phosphinic halide andthe diol taken for the reaction.

It is preferred, for the preparation of the targetmono-hydroxyl-functional dialkyl phosphinates (I-A) or more specifically(I-A-1) or (I-A-2) with the highest possible phosphorus content, toreact dialkyl phosphinic halides having the highest phosphorus contentamongst the dialkyl phosphinic halides (III), with ethylene glycol.

Thus, the compound of formula (I-A-1) having particularly valuableproperties, is that wherein R¹ and R² are each ethyl, k is 1, n is 1, Yis —CH₂CH₂—, and R³ is hydrogen.

Said reactions are carried out at a temperature of between 25° C. and120° C., and preferably between 50° C. and 90° C. Applying a temperaturelower than 25° C. results in a low yield. On the other hand, applying atemperature higher than 120° C. is not advisable since at suchtemperatures undesirable decomposition products may be formed. Inaddition, a catalyst can be used to accelerate reaction for exampleMgCl₂ or ZnCl₂.

In a preferred embodiment the reaction of dialkyl phosphinic halides(III) with an aliphatic diol is carried out in the presence of a strongbase such as sodium hydroxide or potassium hydroxide, in a medium ofboth an organic solvent and an excess aliphatic alcohol. The organicsolvent is selected from aromatic compounds. Especially suitablearomatic solvents are chlorobenzene, ortho-dichlorobenzene, mesitylene,and in particular, toluene and xylene. An effective amount of the baseemployed in the process is in a range of 1-1.2 mol per 1 mol dialkylphosphinic halides (III), and preferably 1-1.05 mol.

Sodium or potassium hydroxide can be employed in a solid form. Waterresulting from the reaction between the diol and the base should beeliminated from the reaction mixture as much as possible prior to theaddition of dialkyl phosphinic halides (III).

In a preferred embodiment, the reaction of dialkyl phosphinic halides(III) with an aliphatic diol and/or polyol is carried out by varying thedegree of partial phosphorylation of the diol and/or polyol. Thephosphorus-containing diol and/or polyol according to the presentinvention comprises at least one phosphorus-containing group. Thisphosphorus-containing group is a group of formula (III-A).

wherein:

wherein R¹ and R² are as defined, and wherein the wavy line indicates abond to a diol or polyol via an oxygen atom.

The phosphorus-containing diol and/or polyol of the invention can alsocomprise two or more phosphorus-containing groups of formula (III-A),wherein these phosphorus-containing groups can be identical ordifferent.

The reaction of dialkyl phosphinic halides (III) with an aliphatic dioland/or polyol can be carried out in the presence of an organic basewhich is selected from, but not limited to, the group of tertiaryamines, for example, triethylamine, pyridine, diisopropyl ethyl amine,1-methylimidazole. The amount of base used is equimolar to dialkylphosphinic halide (III). The base can also be used in excess to thedialkyl phosphinic halide. Said reactions are typically carried out in amedium of inert organic solvent. Suitable solvents for thephosphorylation are, but not limited to, halogenated hydrocarbons, suchas methylene chloride, chloroform or 1,2-dichloroethane. Solvents whichare further suitable are ethers such as dioxane or tetrahydrofuran.Solvents which are further suitable are hydrocarbons such as hexane ortoluene.

In a preferred embodiment the reaction of dialkyl phosphinic halides(III) with an aliphatic diol and/or polyol is carried out in thepresence of a strong inorganic base such as sodium hydroxide orpotassium hydroxide, in a medium of an organic solvent such aschlorobenzene, mesitylene, and in particular, toluene and xylene.

An effective amount of the base employed in the process is in a range of1-1.2 mol per 1 mol dialkyl phosphinic halides (III), and preferably1-1.05 mol. Sodium or potassium hydroxide can be employed in a solidform. Water resulting from the reaction between the diol, and/or polyoland the base should be eliminated from the reaction mixture as much aspossible prior to the addition of dialkyl phosphinic halides (III).

The amounts of dialkyl phosphinic halide (III) and diol and/or polyolcan be adjusted so that the desired degree of functionalization isattained. Partial phosphorylation of the diol and/or polyol can beachieved by using less than the stoichiometric amount of the dialkylphosphinic halide (III) to the diol and/or polyol based on itsfunctionality. In this way, only a portion of the OH groups in the dioland/or polyol is reacted with dialkyl phosphinic halide.

The phosphorus-containing diol and/or polyol of the present invention(also described herein as the partially phosphorylated diol and/orpolyol) has a remaining average OH-functionality (followingphosphorylation thereof) of 1 and a molecular weight of from about 200to about 1000. The phosphorus-containing diols and/or polyols of thepresent invention have a phosphorus content of about 4-20% by weight anda hydroxyl number of about 20-800 mg KOH/g, depending on the dialkylphosphinic halide and the diol and/or polyol taken for the reaction, andon the molar ratio between them.

The diol and/or polyol phosphorylation reactions are carried out at atemperature of between 0° C. and 100° C., and preferably between 10° C.and 90° C. Applying a temperature lower than 0° C. results in a lowreaction rate. On the other hand, applying a temperature higher than100° C. is not advisable since at such temperatures undesirabledecomposition products may be formed.

The mono-hydroxyl-functional dialkyl phosphinate compounds of theinvention are useful as reactive flame retardants. The flame retardantsmay be used in a blend with phosphate compound as described herein, andalso optionally with additional halogenated or non-halogenated products.Some examples of halogenated flame retardants which can be used as thephosphate compound or in addition to the phosphate compound describedherein (where the two are understood to be different) are thechlorinated phosphates such as the non-limiting examples oftris(1,3-dichloro-2-propyl) phosphate (TDCP) and chlorinatedbisphosphates like CR-504L [phosphoric acid esters, oxydi-2,1-ethanediyltetrakis (2-chloro-1-methylethyl) ester] (CAS #s 52186-00-2 &184530-92-5) available from Daihachi, Amgard V6, and Yoke's ELF-800(propylene oxide analogue of Amgard V6). For flexible polyurethane foamsit is preferred to use halogen-free hydroxyl-functional dialkylphosphinates of the invention with halogen-free phosphate compounds.

The phosphate component herein (phosphate compound) can be any phosphatewherein the phosphate is selected from the group consisting of aliphaticphosphates, aromatic phosphates, mixed aromatic aliphatic phosphates,aliphatic bisphosphates, aromatic bisphosphates, mixed aliphaticaromatic bisphosphates, oligomeric phosphates, polymeric phosphates andcombinations thereof. In one embodiment, the aliphatic moieties can beany of alkyl, alkenyl and alkynyl of up to 20 carbon atoms, preferablyup to 12 carbon atoms and most preferably up to 8 carbon atoms. Inanother embodiment, the aryl moieties can contain from 6 to 20 carbonatoms, from 6 to 12 carbon atoms and from 6 to 8 carbon atoms.

In one non-limiting embodiment, the phosphate is of the general formula(VI):

where R⁷, R⁸ and R⁹ are each independently phenyl, alkyl substitutedphenyl, or linear or branched, or saturated or unsaturated alkylcontaining up to 22 carbon atoms, more specifically linear or branched,or saturated or unsaturated alkyl containing from up to 6 carbon atoms,or phenyl, or alkyl substituted phenyl of from 6 to about 22 carbonatoms, even more specifically from 6 to 12 carbon atoms, or linear orbranched alkoxy containing up to 8 carbon atoms, preferably up to 6carbon atoms, R is a divalent alkylene group of from 1 to 3 carbonatoms, and the subscripts a, b and c are each 0 or 1, and when any of a,b, and c are 1, then the respective R⁷, R⁸ and R⁹ bonded thereto is alinear or branched alkoxy containing up to 8 carbon atoms, preferably upto 4 carbon atoms.

Some suitable examples of trialkyl phosphates are triethyl phosphate,tripropyl phosphate, triisopropyl phosphate, tributyl phosphate,tri-tert-butyl phosphate, tris(2-ethylhexyl) phosphate, trioctylphosphate, and combinations thereof.

Some examples of alkoxy phosphates are tris(2-butoxyethyl) phosphate,tris(2-methoxyethyl) phosphate, tris(2-ethoxyethyl) phosphate,tris(2-i-propoxyethyl) phosphate, tris(2-hexoxyethyl) phosphate andcombinations thereof.

In another embodiment herein, the phosphate is of the general formula(VII)

where either (i) only one of R⁸ and R⁹ is a linear or branched orsaturated or unsaturated alkyl containing up to 22 carbon atoms, morespecifically from 6 to 22 carbon atoms and most specifically from 4 to12 carbon atoms, and the other remaining R⁸ or R⁹ moiety is anunsubstituted or 1-4 carbon atoms substituted aryl group of from 6 to 10carbon atoms, or (ii) both of R⁸ and R⁹ are each a linear or branched orsaturated or unsaturated alkyl containing up to 22 carbon atoms, morespecifically from 6 to 22 carbon atoms and most specifically from 4 to12 carbon atoms.

In one embodiment herein the phosphate herein can be selected from thegroup consisting of diethyl phenyl phosphate, ethyl diphenyl phosphate,di-n-propyl phenyl phosphate, n-propyl diphenyl phosphate, di-n-butylphenyl phosphate, n-butyl diphenyl phosphate, di-isobutyl phenylphosphate, isobutyl diphenyl phosphate, di-n-pentyl phenyl phosphate,n-pentyl diphenyl phosphate, di-n-hexyl phenyl phosphate, n-hexyldiphenyl phosphate, 2-ethylhexyl diphenyl phosphate, isodecyl diphenylphosphate, and mixtures thereof.

In one specific embodiment herein, the phosphate is an aromaticphosphate compound, preferably an aromatic phosphate ester containingthree aryl moieties, or a bisphosphate containing four aryl moieties.

Examples of commercial phosphate esters useful herein are triarylphosphate esters such as those selected from the group consisting oftriphenyl phosphate, tricresyl phosphate, mixed phenyl cresylphosphates, trixylyl phosphate, mixed phenyl xylyl phosphates,trimesityl phosphate, mixed mesityl phenyl phosphates,tris(propylphenyl) phosphate, mixed propylphenyl phenyl phosphates,tris(isopropylphenyl) phosphate, mixed isopropylphenyl-phenylphosphates, tris(butylphenyl) phosphate, mixed butylphenyl phenylphosphates, tris(isobutylphenyl) phosphate, mixed isobutyl-phenyl phenylphosphates, tris(t-butylphenyl) phosphate, mixed t-butylphenyl phenylphosphates and combinations thereof.

In yet another embodiment herein, the phosphate is of the generalformula (VIII):

wherein X is the residue of a C₂-C₃₀ dihydroxy compound, or aC₆-C₃₀-dihydroxy aryl compound, R¹⁰, R¹¹, R¹² and R¹³ are eachindependently a C₁-C₈-alkyl, C₃-C₈-cycloalkyl or C₆-C₂₀-aryl, and thesubscript n is an average oligomeric value of from 1 to 10.

In the above formula of aromatic phosphate ester (VIII), the subscript nis preferably 1 to 3, and more preferably 1, X is a residue of anaromatic dihydroxy compound such as hydroquinone, resorcinol,bis(4-hydroxydiphenyl)methane, bisphenol A, dihydroxydiphenyl,dihydroxynapthalene, bis(4-hydroxyphenyl)sulfone, bis(4-hydroxyphenyl)ketone and bis(4-hydroxyphenyl)sulfide, and ispreferably the residue of hydroquinone, resorcinol or bisphenol A, andR¹⁰, R¹¹, R¹², R¹³ are each independently the residue of an aromaticmonohydroxy compound such as phenol, cresol, xylenol, isopropylphenol,butylphenol and p-cumylphenol, and preferably are each independently theresidue of phenol, cresol or xylenol.

Further, as the phosphate component herein are the aromatic bisphosphateesters including those selected from the group consisting ofhydroquinone bis(diphenyl phosphate), resorcinol bis(diphenyl phosphate)(Fyrolflex® RDP, ICL-IP America, Tarrytown, N.Y.), bisphenol Abis(diphenyl phosphate) (Fyrolflex® BDP, ICL-IP America, Tarrytown,N.Y.), neopentyl glycol bis(diphenyl phosphate), propylene glycolbis(diphenyl phosphate), and their combinations. Of these phosphateesters, resorcinol bis(diphenyl phosphate) and bisphenol A bis(diphenylphosphate) and combinations thereof are most preferred.

The flame retardant blend(s) herein will contain from 25 to 95% byweight phosphate, specifically from 50% to 90% by weight of phosphate,more specifically from 70 to 90% by weight of phosphate, based on thetotal weight of the flame retardant blend.

The phosphate herein can be prepared by any one of several known andconventional processes, e.g., the aromatic phosphate can be prepared bythe reaction of phosphorus oxychloride with an aromatic dihydroxycompound such as any of those aforementioned, in the presence of a Lewisacid catalyst, e.g., aluminum chloride, magnesium chloride or titaniumtetrachloride, etc., removing unreacted phosphorus oxychloride from theresulting reaction mixture and thereafter reacting the latter with anaromatic monohydroxy compound such as any of those aforementioned toprovide an aromatic phosphate ester. In a variation of this process, anaromatic phosphate ester is obtained by reacting phosphorus oxychloridewith a mixture of aromatic monohydroxy compound and aromatic dihydroxycompound.

In one embodiment, the flame retardant blends as described herein areprovided such that the hydroxyl-functional dialkyl phosphinate andphosphate component(s) are blended with reactive brominated productscontaining a hydroxyl-group. For flexible PU foams as described hereinit is preferred to use pure halogen-free hydroxyl-functional dialkylphosphinate(s) of the invention with phosphate compound.

The mono-hydroxyl-functional dialkyl phosphinate compounds of thepresent invention are highly efficient reactive flame retardants whenincorporated into flexible polyurethane foams with phosphate compound.It should be noted that the flame retardant blend(s) of the inventionare useful over a broad Isocyanate Index (abbreviated herein MDI orTDI). The index refers to the ratio of isocyanate practically used inthe formulation vs. the theoretical stoichiometric amount of isocyanaterequired, expressed in percentages.

The flexible polyurethane foams herein contain a typicalflame-retardant-effective amount of the flame retardant blend of thisinvention. Typically, the flame retardant blends of this invention areapplied in amounts that provide a total phosphorus concentration in thepolymer (i.e., the flexible polyurethane foam) in the range of 0.3 to 15wt %, based on the total weight of the polymer. Preferably, the totalphosphorus concentration in the polymer is in the range of 1 to 10 wt %and more preferably, in the range of 1.5 to 5 wt %, based on the totalweight of the flexible polyurethane polymer. Most preferably, theamounts used of the flame retardant blend(s) of this invention are atleast sufficient to meet the current requirements of the flammabilityTest Method MVSS 302.

By suitable choice of components and conditions, the flexiblepolyurethane foams are made which may vary in properties as to thedegree of flexibility. Thus, flexible foams are generally made frompolymeric diols or triols having hydroxyl numbers of from 20 to 80 usingwater as the principal foaming agent.

The flexible polyurethane foams of the present invention can contain theappropriate choice of auxiliary agents, for example catalysts,surfactants, foam stabilizers and the like.

Flexible polyurethane foams as used herein is made using a diol and/orpolyol having a 3,000 to about 6,000 molecular weight diol and/or polyolas described herein, e.g., a polyether triol prepared by the addition ofpropylene oxide to glycerol. A flexible polyurethane foam as used hereinis characterized by having a core impact resilience of at most 30% and aglass transition point of from −80° C. to −60° C. Here, the flexiblepolyurethane foam preferably has a hard segment content of at most 40mass %. Conventional flexible polyurethane foam having a bulk foamdensity of 2.5 pounds per cubic foot (PCF) or lower and having a foamhardness or IFD (measured in accordance with test method ASTM 3574-TestB1) in a range of 10 to 90 lb/50 in².

The method of making the flexible polyurethane foam of the invention cancomprise combining the diol and/or polyol component and/or theisocyanate component or catalyst and one or more of the flame retardantmaterials of Formulae (I-A), (I-A-1), (I-A-2) and (I-B) and phosphatecompound(s) described herein which may be metered and pumped into acommon mixing vessel, and then the resulting mixture may be easily bemoved to the polymerization site for use in molds, slab stockoperations, etc.

The reactive flame retardants and phosphate compound(s) of the inventionherein may also be admixed with the diol and/or polyol reactant beforecombination with the isocyanate reactant. It is also within the scope ofthe invention to mix the reactive flame retardant materials andphosphate compound with the isocyanate before combining such mixturewith the diol and/or polyol reactant. However, if the isocyanate and theaforementioned flame retardant materials are mixed and allowed to standat room temperature for a substantial period of time, reaction mayoccur. The “reaction product” as used in the claims and specificationherein, can in one embodiment comprise reacting the contents of theflexible polyurethane foam-forming system in any one of theaforementioned methods, and may further include reacting the reactiveflame retardant via a pre-polymer technique, such as for example,reacting an excess of isocyanate with polyol to form an isocyanateterminated pre-polymer and then further reacting the prepolymer with thereactive flame retardant and phosphate compound herein.

The flame retardant materials of Formulae (I-A), (I-A-1), (I-A-2) and(I-B) described herein may be described as isocyanate-reactive(NCO-reactive) materials, i.e., they are reactive with the isocyanatesthrough the hydroxyl group(s).

The diols and/or polyols used in making the flexible polyurethane foamsdescribed herein can include any organic polyol, including diols,polyols, and polyether, polyester, polyesteramide polyols havinghydrogen atoms that are reactive with isocyanates may be used.Generally, these materials have molecular weights ranging from about 62to about 5,000 and have from 2 to about 10 or more hydroxyl groups permolecule and weight percent hydroxyl contents ranging from about 0.5 toabout 25%. The generally have hydroxyl numbers of from about 50 to ashigh as 500 or even 700.

In the polyester-polyol type of reactant the acid number should be lessthan 10 is usually as close to 0 as possible. These materials arereferred to conveniently as the “polyol” reactant. The useful activehydrogen-containing diol and/or polyols include the large family ofadduct compounds which result when ethylene oxide, propylene oxide, 1,2-and 2,3-butylene oxide, or other alkylene oxides are added to suchactive hydrogen compounds such as diols, glycols and polyols presentedby ethylene glycol, propylene glycol, glycerine, methyl glucoside,sucrose, sorbitol, hexanetriol, trimethylol propane, pentaerythritol aswell as various alkylamines and alkylenediamines, andpolyalkylenepolyamines and the like. Various amounts of these alkyleneoxides may be added to the base diol, polyol or amine molecules referredto, depending upon the intended use of the polyurethane.

For example, a diol and/or polyol for use in making flexible foams couldbe well represented by glycerine to which sufficient propylene oxide wasadded to give a final hydroxyl content of about 1.7%. Such a materialwould have a molecular weight of about 3,000 and have a molar ratio ofglycerine to propylene oxide of about 1 glycerine to 50 propylene oxide.

This technique of controlling flexibility by selection of the dioland/or polyol molecule and the subsequent amount of alkylene oxide addedis well known to those in the art.

In addition to the glycols and the like which can serve as the basepolyol molecule for addition of the alkylene oxides and thus yield the“polyol” molecule for reaction with the isocyanate, one can use astarting molecule which contains primary and/or secondary amine groupswhich have hydrogen reactive toward alkylene oxides. Here also, thequantity of alkylene oxide added depends on the intended uses of thefinal polyurethane products. In the flexible polyurethane productsherein alkylene oxide would be used to produce polyols with lowerhydroxyl content, such as from about 0.1% to about 5% or 10%.

Representative amines which may serve as active-hydrogen containingmolecules for reaction with epoxides are those having from 1 to about 6or more amino nitrogens, examples of which are ethyl amine, ethylenediamine, diethylenetriamine, triethylenetetramine,tetrapropylenepentamine and other linear saturated aliphatic alkyleneamines, the important requirement being at least two, and preferablymore, say 3 to 8 or 10 active hydrogen sites to which the alkylene oxidemay be added.

It is also well known to use the hydroxyl bearing molecules which havebeen prepared by esterification type reactions from polyfunctional acidsor anhydrides and polyfunctional alcohols as the active hydrogencompounds used in preparing the polyurethane systems. These compoundsare often called polyester polyols. Typical acids used in making thesepolyester polyols are maleic, phthalic, succinic, fumaric,tetrahydrophthalic, chlorendic, and tetrachlorophthalic acids. Typicaldiols and/or polyols are ethylene, propylene, butylene, diethylene, anddipropylene, glycols, and polyethylene, polypropylene, glycols andglycerine, trimethylol propane, hexanetriol, pentaerythritol, sorbitoland the like. Where available the above mentioned acids may be used inthe anhydride form if desired.

In making the polyester-polyols, any of the various polyfunctional acidsor anhydrides or mixtures thereof are caused to react with any of thediols, glycols or polyols or mixtures thereof, using a stoichiometricexcess of the hydroxyl groups such that the final polyol productcontains predominantly hydroxyl end groups. The degree of hydroxylfunctionality and the percent hydroxyl is easily varied to provide thedesired polyols by technology and techniques which are known to thoseskilled in the art.

In the art and technology of making flexible polyurethanes, it is alsoknown to employ what is called prepolymer techniques. This is atechnique wherein part of the reaction involved in making flexiblepolyurethane is carried out yielding a prepolymer of increased molecularweight and with either resultant end groups of hydroxyls or isocyanatesdepending on the stoichiometric used in making this prepolymer. Thisprepolymer is then used to prepare the final flexible polyurethaneproduct by reacting it with either a isocyanate or polyol, depending on,as mentioned above, whether the terminal groups of the prepolymer arehydroxyls or isocyanates, respectively.

Broadly, any of the prior art polyesters, isocyanate-modified-polyesterprepolymers, polyesteramides, isocyanate-modified-polyesteramides,alkylene glycols, isocyanate-modified alkylene glycols, polyoxyalkyleneglycols, isocyanate-modified polyoxyalkylene glycols, etc., having freereactive hydrogens and especially hydroxyl groups may be employed forthe production of the polyurethanes described herein.

Examples of isocyanates which can be used include those having two ormore isocyanate groups which have heretofore been used for makingflexible polyurethane foams. Examples of such isocyanate compoundsinclude aromatic isocyanates, aliphatic isocyanates and alicyclicisocyanates, as well as mixtures of two or more of such isocyanates, andmodified isocyanates obtained by the modification of such isocyanates.Specific examples of such isocyanates are toluene diisocyanate,diphenylmethane diisocyanate, polymethylene polyphenylene polyisocyanate(crude MDI), xylylene diisocyanate, isophorone diisocyanate andhexamethylene diisocyanate; and modified products of such isocyanates,such as carbodiimide-modified products, biuret-modified products, dimersand trimers. Prepolymers with terminal isocyanate groups obtained fromsuch isocyanates and active hydrogen-containing compounds can also beused.

In one embodiment, the isocyanate index range for flexible polyurethanefoams can be from about 130 to about 80, more preferably, from about 120to about 90 and most preferably from about 115 to about 95.

As the blowing agent in the flexible polyurethane foam-formingcomposition of the present invention, known blowing agents heretoforeused in such compositions are suitably selected according to theproperties required of the foamed product.

In the present invention, a cross-linking agent is also used as the caserequires.

As the cross-linking agent, a compound having at least two functionalgroups having active hydrogen, such as hydroxyl groups, primary aminogroups or secondary amino groups is preferred. However, in a case wherea polyol compound is used as the cross-linking agent, the following istaken into account. Namely, a polyol compound having a hydroxyl value ofat least 50 mg KOH/g and more than four functional groups, is consideredto be the cross-linking agent, and a polyol which does not satisfy this,is considered to be any one of polyols of the above-mentioned polyolmixture (polyol (1), (2) or other polyol). Further, two or morecross-linking agents may be used together. As specific examples, apolyhydric alcohol such as dextrose, sorbitol or sucrose; a polyolhaving an alkylene oxide added to a polyhydric alcohol; an aminecompound such as monoethanolamine, diethanolamine, ethylenediamine,3,5-diethyl-2,4 (or 2,6)-diaminotoluene (DETDA),2-chloro-p-phenylenediamine (CPA), 3,5-bis(methylthio)-2,4 (or2,6)-diaminotoluene, 1-trifluoromethyl-4-chloro-3,5-diaminobenzene,2,4-toluenediamine, 2,6-toluenediamine,bis(3,5-dimethyl-4-aminophenyl)methane, 4,4′-diaminodiphenylmethane,m-xylylenediamine, 1,4-diaminohexane, 1,3-bis(aminomethyl)cyclohexane orisophoronediamine; and a compound obtained by adding an alkylene oxidethereto, may, for example, be mentioned.

When the above cross-linking agent is used, even in a case where, forexample, a large amount of a blowing agent is used to produce a flexiblefoam having a low density, the foaming stability will be good, and itwill be possible to produce such a flexible foam. Especially when a dioland/or polyol having a high-molecular weight is used, it is possible toproduce a flexible foam having a low density which used to be considereddifficult to foam. Further, when the cross-linking agent is used, thedurability will be improved, as compared with a case where it is notused. In a case where a diol and/or polyol having a high-molecularweight is used as in the present invention, the foaming stability canreadily be improved particularly when a compound having a relativelyhigh-molecular weight, such as a molecular weight of at least 4000, isused.

Water is a typical example of such a blowing agent; other examplesinclude methylene chloride, n-butane, isobutane, n-pentane, iso-pentane,dimethyl ether, acetone, carbon dioxide, and the like. Depending on thedesired density and other properties of the foamed polyurethane, theseand other blowing agents can be used alone or in combinations of two ormore in a manner known in the art.

The amount of blowing agent to be used is not particularly limited butwill ordinarily range from 0.1 to 20 parts by weight per 100 parts byweight of the diol and/or polyol component of the foam-formingcomposition. Preferably, the amount of blowing agent(s) will be such asto provide a foam density of from 0.8 to 2.5 pounds per cubic foot, andpreferably from 0.9 to 2.0 pounds per cubic foot.

The polyurethane foam-forming composition herein can preferably containany of the catalysts, and combination of catalysts, heretofore known orused for the production of polyurethane foams. Examples of usefulcatalysts include sodium hydroxide, sodium acetate, tertiary amines ormaterials which generate tertiary amines such as trimethylamine,triethylene diamine, N-methyl morpholine, N,N-dimethyl cyclohexylamine,and N,N-dimethyl aminoethanol. Also applicable are metal compounds suchas hydrocarbon tin alkyl carboxylates, dibutyl tin diacetate, dibutyltin dioctoate dibutyl tin dilaurate and stannous octoate; as well asother compounds intended to promote trimerization of the isocyanate suchas, 2,4,6-tris(N,N-dimethylamino-methyl)phenol,1,3,5-tris(N,N-dimethyl-3-aminopropyl)-S-hexahydrotriazine, potassiumoctoate, potassium acetate and catalysts such as DABCO TMR® and POLYCAT43®.

Many other kinds of catalysts can be substituted for those listed above,if desired. The amount of catalyst used can advantageously range from0.05 to 5 weight percent or more based on the total weight of dioland/or polyol in the foam-forming mixture.

The isocyanate (NCO) index which is applied in making the flexible foamaccording to the present invention is 95-125 and preferably 100-120. Itis commonly understood that the NCO index of polyurethane foams is fromabout 80-130.

The densities of the flexible polyurethane foams herein may range offrom 14-80 and preferably 16-55 and most preferably 20-40 kg/m³.

Surfactants, including organic surfactants and silicone-basedsurfactants, may be added to serve as cell stabilizers. Somerepresentative materials are sold under the designations SF-1109, L-520,L-521 and DC-193, which are, generally, polysiloxane polyoxylalkyleneblock copolymers. Also included are organic surfactants containingpolyoxy-ethylene-polyoxybutylene block copolymers. It is particularlydesirable to employ a minor amount of a surfactant to stabilize thefoaming reaction mixture until it cures. Other surfactants that may beuseful herein are polyethylene glycol ethers of long-chain alcohols,tertiary amine or alkanolamine salts of long-chain allyl acid sulfateesters, alkylsulfonic esters, alkyl arylsulfonic acids, and combinationsthereof. Such surfactants are employed in amounts sufficient tostabilize the foaming reaction against collapse and the formation oflarge uneven cells. Typically, a surfactant total amount from about 0.2to about 3 wt %, based on the formulation as a whole, is sufficient forthis purpose. However, it may be in some embodiments desirable toinclude some surfactants, e.g., DABCO DC-5598, available from AirProducts and Chemicals, Inc., in a higher amount. In view of this asurfactant may be included in the inventive formulations in any amountranging from 0 to 6 wt. %, based on the diol and/or polyol component.

Finally, other additives such as fillers and pigments may be included inthe polyurethane foam-forming formulations described herein. Such mayinclude, in non-limiting embodiments, barium sulfate, calcium carbonate,graphite, carbon black, titanium dioxide, iron oxide, microspheres,alumina trihydrate, wollastonite, prepared glass fibers (dropped orcontinuous), polyester fibers, other polymeric fibers, combinationsthereof, and the like. Those skilled in the art will be aware withoutfurther instruction as to typical and suitable means and methods toadapt the inventive formulations to produce flexible polyurethane foamsthat, though still falling within the scope of the claims appendedhereto, exhibit or benefit from desired property and/or processingmodifications.

The flexible polyurethane foams described herein, be they be can beutilized in the construction and formation of various articles such asfurniture, bedding, and automotive seat cushions, more specifically,furniture applications, automotive applications, boating applications,bus seating applications, train seating applications, RV seatingapplications, office furniture seating applications, aviationapplications, tractor applications, bicycle applications, engine mountapplications, compressor applications, bedding applications, insulationapplications, sporting goods applications, shoe applications, carpetcushioning applications, packaging applications, textile applications,buffer cushioning applications, HVAC applications, tent applications,life raft applications, luggage applications, and hand bag applications.

Flexible slabstock polyurethane foam can be used for furniture, e.g.,upholstered furniture, such as cushions, backs and arms, the automotiveindustry, such as seat and back cushions, and head linings and headrests, for automobiles and trucks, for public transport seating, such asbusses and airplanes, as well as in any of tractor, bicycle andmotorcycle seats including, but not limited to vehicle seat bottom andback bolsters, and armrests, as well as support rings for run flattires, and other automobile interior components; bedding such asmattresses, as sound insulation materials, automobile interiorcomponents such as an arm rest, a steering wheel and a shift lever knob,shoe soles, and sporting goods.

The following examples illustrate specific embodiments of both thepreparation of certain compounds of the invention and the utility ofthese compounds as reactive flame retardants in flexible polyurethanefoams.

EXAMPLES Preparation Example 1

A 2-liter, jacketed, hastelloy reactor equipped with a mechanicalstirrer, oil heater and positive displacement laboratory pump wascharged with diethyl phosphinic acid (779 g, 6.38 mol) and sealed. Thereactor was heated to an internal temperature of 45° C. Propylene oxide(743 g, 12.77 mol) was added to the reactor via the pump over two hourswith the temperature being maintained below 65° C. Subsequently thereactor internal temperature was increased to 90° C. and maintainedthere for three hours. The excess propylene oxide was evaporated and theresidue was distilled under vacuum (300-500 mTorr) using a wiped filmevaporator at a jacket temperature of 125° C. The target fraction wascollected as a clear, colorless liquid. The yield was 90% with respectto the starting diethyl phosphinic acid. The product was a mixture oftwo isomers of hydroxyl-functional esters of diethyl phosphinic acid,³¹P NMR (acetic acid-d₄, ppm): 66.8-67.7; and had an acid # of 0.4 mgKOH/g and a phosphorus content of 15.9%.

Preparation Example 2

A 1-liter flask, with a heating mantle, mechanical stirrer, refluxcondenser, dip tube, j-chem controller and thermocouple, and causticscrubber was charged with diethyl phosphinic acid (469 g, 3.84 mol). Theflask was heated to 80° C. and ethylene oxide from a pressurizedcylinder was charged into the reactor through the dip tube over fivehours. Final molar ratio of ethylene oxide to diethyl phosphinic acidwas 1.33. The reaction mixture was kept at 80° C. for additional threehours. Further nitrogen was passed through the dip tube to remove theexcess ethylene oxide. A batch distillation of the residue was done at150° C. and 200 mTorr resulting in a clear liquid (400 g). The productwas 2-hydroxyethyl ester of diethyl phosphinic acid, ³¹P NMR (CDCl₃,ppm): 79; and had an acid # of 0.4 mg KOH/g.

Application Example 3

MVSS 302 Test: This test is a horizontal flame test that is used as aguideline for automobile manufactures. The sample size was 14″×4″×½″.There is a line 1½″ from the ignition point. A flame was ignited forfifteen seconds. The ignition source was then turned off and the samplewas rated. A “DNI” rating indicates that the sample did not supportcombustion (“did not ignite”). A rating of “SE” indicates that thesample ignited but did not burn to the timing zone, which is a pointstarting from the 1½″ mark to the 3½″ line. A rating of “SENBR”indicates that the sample burned past the 1½″ line but was extinguishedbefore the 3½″ mark. A rating of “SE/B” indicates that a sample burnedpast the 3½″ mark but was extinguished before the endpoint. An inch perminute rate was then calculated. The burn rate indicates that a sampleburned passed the 3½″ mark. An indication of a burn rate or an SE/Brating that was higher than 4.0 in/min indicates failure in accordancewith this test. For this study a minimum performance of SENBR wasrequired.

COMPRESSION SET 90% was determined according to ASTM D3574.

Materials:

Desmophen 60WB01 is a polyester polyol available from Covestro.BPPE and BPPE-HP are butylated triaryl phosphates available from ICL-IPAmerica.BDP is bisphenol-A bis(diphenyl phosphate) available from ICL-IPAmerica.TBEP is a tris(2-butoxyethyl) phosphate available from ICL-IP America.ADP is an isodecyl diphenyl phosphate available from ICL-IP America.Niax C-131NPF is an amine catalyst available from Momentive.Niax DMP is an amine catalyst available from Momentive.Niax L-537XF is a silicone stabilizer available from Momentive.TD 80 is an isocyanate material available from BASF.TD 65 is an isocyanate material available from Covestro.A/B ratio is the ratio of TDI to the rest of the formulationingredients.

RPE (reactive phosphinate ester of the invention) which is the reactivephosphinate ester produced in Preparation Example 1 above, is used inthe Application Examples 3 and 4 herein below, which RPE showed highefficiency in the MVSS 302 test shown above, passing with a SE rating atonly 4 parts in a 1.8 pcf density polyurethane foam. Butylated triarylphosphate ester products like BPPE and BPPE-HP (low TPP content version)require 10 parts to pass with a SE rating. A bisphosphate product likeBDP requires 12 parts to pass with a SENBR rating. It was unexpectedlyfound that a 20/80 blend of RPE and a phosphate ester like the BPPE typeproducts could also pass the MVSS 302 with a SE rating at only 4 parts,and a similar blend with a bisphosphate like BDP could pass with a SENBRrating at the same loading. These blends have similar efficiency to 4parts of RPE and only contain 0.8 parts of the high efficiency reactiveFR product. The majority of each blend consist of the low efficiencyphosphate ester products BPPE and BDP. Even 6 parts of a 20/80 blend ofRPE and a phosphate ester like TBEP passes with a SE rating. 8 parts ofa 20/80 blend of RPE and a phosphate ester like isodecyl diphenylphosphate passes with a SENBR rating.

Since it is unrealistic to expect such high FR efficiency from such alow level of the RPE (0.8 parts) in the presence of low efficiencyphosphate ester products (3.2 parts), it is clear there is a synergisticrelationship between the reactive phosphinate ester product RPE andvarious phosphate esters. The phosphinate/phosphate ester blends shownbelow contain 30-35% less phosphorus than the RPE product and stillretain the same FR efficiency. It is also clear from the latter twoexamples shown in the table in Application Example 3 herein below, whereRPE is blended with the trialkyl phosphate ester product TBEP and ADPproduct that this synergistic property extends to a variety of phosphateester products.

In addition to holding the flammability performance at a high level withthese RPE/phosphate ester blends, it is important to note that thephysical properties of the resulting foams (e.g., compression set) aregreatly improved over what is observed using the RPE product alone.Reactive flame retardant products are known to disrupt the normalfoam-forming process, resulting in poor foam physical properties. Inmost cases this is easily observed by a loss of the foam's ability torecover after compression at an elevated temperature. Compression settesting according to ASTM D3574 is a common foam requirement, andensures compressed foam will indeed rebound. By using a small amount ofthe RPE product in the phosphinate/phosphate ester blends, the negativeeffects of using a reactive FR product can be avoided while at the sametime retaining the high FR efficiency required in the end useapplication. The RPE/phosphate ester blends retain both excellent FRperformance and also good physical properties.

Experiment ID Comp Comp Comp Comp Example Example Example Comp Comp Ex#1 Ex #2 Ex #3 Ex #4 #1 #2 #3 Ex #5 Ex #6 FR Used BPPE/ BPPE-HP/ BDP/TBEP/ ADP/ OH # % P BPPE BPPE-HP BDP RPE RPE RPE RPE RPE RPE Desmophen60WB01 60 100 100 100 100 100 100 100 100 100 BPPE 8.5 10.0 BPPE-HP 7.910.0 BDP 8.9 12.0 RPE 410 14.7 4.0 BPPE/RPE (80/20) 82 9.7 4.0BPPE-HP/RPE (80/20) 82 9.3 4.0 BDP/RPE (80/20) 82 10.1 4.0 TBEP/RPE(80/20) 82 9.2 6.0 ADP/RPE (80/20) 82 9.3 8.0 Niax C-131NPF 0 — 1.1 1.11.1 1.1 1.1 1.1 1.1 1.1 1.1 Niax DMP 0 — 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.20.2 Niax L-537XF 0 — 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 Water 6233 —4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0 Total 116.6 116.6 118.6 110.6 110.6110.6 110.6 112.6 114.6 A-side: TD 80 18.8 18.8 18.8 19.8 19.0 19.0 19.019.1 19.2 A-side: TD 65 28.2 28.2 28.2 29.7 28.5 28.5 28.5 28.7 28.8Index 98 98 98 98 98 98 98 98 98 A/B Wt Ratio 0.40 0.40 0.40 0.45 0.430.43 0.43 0.42 0.42 % P in the foam 0.52 0.48 0.65 0.37 0.25 0.24 0.260.34 0.46 Observations Lab Temp deg F. or C. 75 75 75 75 75 75 75 75 75Crm time sec 8 8 7 7 7 7 7 7 7 Blow off/End of Rise sec 76 81 77 63 6968 69 73 75 Blow off spots multiple multiple multiple multiple multiplemultiple multiple multiple multiple Sighback No No No No No No No No NoPhysical Performance Air flow scfm 0.6 0.7 0.7 0.6 0.6 0.5 0.7 0.5 0.9Density pcf 2.02 2.11 2.20 1.99 1.85 1.88 1.82 1.96 1.93 90% CompressionSet % 46 45 26 67 32 36 21 40 21 Fire Performance MVSS-302 SE SE SENBRSE SE SE SENBR SE SENBR

Application Example 4

Formulations Experiment ID Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex.8 Ex. 9 FR Used BPPE/RPE BPPE/RPE BPPE/RPE BDP/RPE BDP/RPE BDP/RPE OH #% P BPPE (80/20) (60/40) (40/60) RPE BDP (80/20) (60/40) (40/60)Desmophen 60WB01 60 100 100 100 100 100 100 100 100 100 BPPE 8.5 10BPPE/RPE (80/20) 73 10 4 BPPE/RPE (60/40) 146 11.5 4 BPPE/RPE (40/60)219 12.9 4 RPE 365 15.9 4 BDP 8.9 12 BDP/RPE (80/20) 73 10.3 4 BDP/RPE(60/40) 146 11.7 4 BDP/RPE (40/60) 219 13.1 4 Niax C-131NPF 0 — 1.1 1.11.1 1.1 1.1 1.1 1.1 1.1 1.1 Niax DMP 0 — 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.20.2 Niax L-537XF 0 — 1.30 1.30 1.30 1.30 1.30 1.30 1.30 1.30 1.30 Water6233 — 4 4 4 4 4 4 4 4 4 Total 116.6 110.6 110.6 110.6 110.6 118.6 110.6110.6 110.6 A-side: TD 80 18.8 19 19.2 19.4 19.7 18.8 19 19.2 19.4A-side: TD 65 28.2 28.5 28.8 29 29.6 28.2 28.5 28.8 29 Index 98 98 98 9898 98 98 98 98 A/B Wt Ratio 0.40 0.43 0.43 0.44 0.45 0.40 0.43 0.43 0.44% P in the foam 0.55 0.27 0.31 0.35 0.42 0.69 0.28 0.31 0.35Observations Lab Temp deg F. or C. 75 75 75 75 75 75 75 75 75 Crm timesec 8 7 6 6 7 7 8 7 7 Blow off/End of Rise sec 76 68 67 70 65 77 70 7066 Blow off spots multiple multiple multiple multiple multiple multiplemultiple multiple multiple Sighback No No No No No No No No No PhysicalPerformance Air flow scfm 0.6 0.8 0.6 0.5 0.8 0.7 0.4 0.6 0.7 Densitypcf 2.02 1.85 1.87 1.86 1.82 2.20 1.90 1.83 1.83 Fire PerformanceMVSS-302 SE SE SE SE SE SENBR SENBR SENBR SE

Summary Illustrating Synergy

See FIG. 1 for below table

RPE/BPPE Blends Percentage of Reactive in Blend 0 20 40 60 100 FRLoading in Foam (pph) 10 4 4 4 4 MVSS 302 Rating SE SE SE SE SE FRloading needed to pass MVSS 302 with a SE ratingSee FIG. 2 for below table

RPE/BDP Blends Percentage of Reactive in Blend 0 20 40 60 100 FR Loadingin Foam (pph) 12 4 4 4 4 MVSS 302 Rating SENBR SENBR SENBR SE SE FRloading needed to pass MVSS 302 with a SENBR or better rating

The straight dotted lines in both FIG. 1 and FIG. 2 is the level offlame retardant loading one would expect based on a simple linearrelationship between the two flame retardants described therein if nosynergy was present. Any points below the dotted line (the solid line)in each of FIGS. 1 and 2 provide evidence that much less flame retardantwas needed than would be expected based on the simple linearrelationship between the passing levels for the two flame retardantproducts. The fact the blends require less flame retardant than would beexpected is evidence of a synergistic relationship between the two flameretardants in the blend.

While the invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiments disclosed as the best modecontemplated for carrying out this invention but that the invention willinclude all embodiments falling within the scope of the appended claims.

1.-15. (canceled)
 16. A flame-retardant blend comprising: (A) aphosphorus-containing polyol reaction product of the partialphosphorylation of a polyalcohol, which phosphorus-containing polyolreaction product comprises at least one phosphorus-containing group, ofthe formula (I-B):

wherein: R¹ and R² are independently selected from a linear or branchedalkyl group containing from 1 to 4 carbon atoms, n¹ is an integer equalto or greater than 1 and n² is one, with n¹+n² being equal to or greaterthan 2, and Z² is a moiety derived from a branched polyol which has avalence of n¹+n², and is of the general formula:

wherein R is selected from the group consisting of:

and where each R⁶ independently is H or is an alkyl of from 1 to 4carbon atoms, x is ≥1, y is 2 or 3; z is an integer of from 2 to 5; and,m≥1; and, (B) a phosphate compound.
 17. The flame-retardant blend ofclaim 16, wherein R¹ and R² are each an ethyl group.
 18. The flameretardant blend of claim 16, wherein the phosphate compound is selectedfrom the group consisting of mixed t-butylphenyl phenyl phosphates,resorcinol bis(diphenyl phosphate), bisphenol A bis(diphenyl phosphate),tris (2-butoxyethylphosphate), and combinations thereof.
 19. The flameretardant blend of claim 16 further comprising a halogenated phosphatecompound selected from the group consisting oftris(1,3-dichloro-2-propyl) phosphate (TDCP); phosphoric acid esters,oxydi-2,1-ethanediyl tetrakis (2-chloro-1-methylethyl) ester; Amgard V6(2,2-bis(Chloromethyl)-1,3-propanediyl tetrakis(2-chloroethyl) EsterPhosphoric Acid); ELF-800 (2,2-bis(Chloromethyl)-1,3-propanediyltetrakis(2-chloro-1-methylethyl) Ester Phosphoric Acid); andcombinations thereof.
 20. A flame-retarded flexible polyurethane foamcomprising the reaction product of a polyol, an isocyanate and a flameretardant-effective amount of the flame-retardant blend of claim
 16. 21.An article comprising the polyurethane foam of claim
 20. 22. Anapplication comprising the article of claim 21, wherein the applicationis selected from the group consisting of furniture applications,automotive applications, boating applications, bus seating applications,train seating applications, RV seating applications, office furnitureseating applications, aviation applications, tractor applications,bicycle applications, engine mount applications, compressorapplications, bedding applications, insulation applications, sportinggoods applications, shoe applications, carpet cushioning applications,packaging applications, textile applications, buffer cushioningapplications, HVAC applications, tent applications, life raftapplications, luggage applications, and hand bag applications, whichcomprises the flexible polyurethane of claim
 1. 23. The furnitureapplication of claim 22, which is upholstered furniture.
 24. Theautomotive application of claim 22, which is selected from the groupconsisting of automotive seat cushions, head linings and head rests,back cushions for automobiles and trucks, bus seating, vehicle seatbottom and back bolsters, armrests, support rings for run flat tires,and other automobile interior components.
 25. The bedding application ofclaim 22 which is selected from the group consisting of mattresses andmattress top applications.
 26. The insulation application of claim 22,which is a sound insulation material.